I recently shot footage on a sony PMW Ex-1.  1080/50i in HQ mode, 35Mbs.  I used Sony Clip Browser v2 to export these files as MXF to a shared drive on our network.  I then opened a new 1080/50i project in Avid media Composer v2.8.3 and imported these MXF files using the DNxHD 120 MXF resolution onto an Avid Unity Drive.  So far so good.

However, when attempting to edit with these clips I get the following error message...

Exception: DecpompStream::GetStreamingLongGOPFrame error setting decode params, status 1

Has anyone esle had a similar experience and if so what is the solution?  I appreciate your help and apologies if this has been covered elsewhere.  I have contacted Avid support about this matter who say that the EX-1 is not a supported device.

 I have the same camera and had a similar problem.  If I remember correctly, part of my problem was to get 2.8.3 (which you already have) and also download the latest version (or drivers?) of the Clip Browser...  Ex-1 not a supported device?  Their manual states support for Sony XDCAM in many places...?  At any rate, I hope I helped or at least triggered some thoughts in places to look.

FYI - I have no problem using EX-1 MXF files imported into MC 3.0, using Clip-Browser 1.02 or 2.0. I don't think I had any trouble with 2.8.3 but I think earlier versions did not work.